Two sensitivity levels of cattle oocytes to puromycin.
Germinal vesicle breakdown (GVBD) in cumulus-enclosed and denuded cattle oocytes was sensitive to puromycin at concentrations at or above 50 micrograms/ml. Media supplemented with 5-25 micrograms/ml of puromycin did not significantly reduce either rate or sequence of GVBD after 8 h of culture (82-96% GVBD). In concentrations of 50, 75, and 100 micrograms/ml, GVBD occurred in 15, 4, and 2% of oocytes, respectively. However, 50 micrograms puromycin/ml did postpone the time sequence of GVBD, since all treated oocytes underwent GVBD after 20 h of culture. Oocytes arrested in the germinal vesicle (GV) stage possessed GV filled with highly condensed bivalents. The puromycin block (100 micrograms/ml) was fully reversible, and the time sequence of GVBD was two times faster than in control medium. Proteins important for GVBD were synthesized during the first 4 h of culture, and 81% of oocytes underwent GVBD when puromycin (100 micrograms/ml) was added after 4 h of preincubation in control medium. The first polar body (I PB) expulsion was more sensitive to inhibition of protein synthesis, as shown by the observation that 2.5 and 5 micrograms puromycin/ml significantly (69 and 61%) reduced the incidence of Metaphase II, and 10 micrograms/ml highly significantly (31%) reduced it. The I PB expulsion in concentrations of 25 and 37 micrograms puromycin/ml was less than 5%. The subsequent culture in puromycin (8 h) and 6-dimethylaminopurine (8 h) proved that nuclear membrane breakdown is less sensitive to inhibition of protein phosphorylation than the process of chromatin condensation.
Motlík
J
J
Czechoslovak Academy of Sciences, Libĕchov.
Lie
B
B
Shioya
Y
Y
D000225:Adenine / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D002417:Cattle; D004305:Dose-Response Relationship, Drug; D005260:Female; D066298:In Vitro Techniques; D008540:Meiosis / Q000187:drug effects; D009865:Oocytes / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D014176:Protein Biosynthesis; D011691:Puromycin / Q000008:administration & dosage / Q000494:pharmacology*; D013997:Time Factors
D011691:Puromycin; C001020:N(6),N(6)-dimethyladenine; D000225:Adenine